This invention relates generally to spring assemblies for mattress, cushions and other bedding or seating products and, more particularly, to a pocketed coil spring assembly and associated method of manufacturing such an assembly.
A well known type of bedding or seating product comprises a spring assembly which includes a number of discrete coil springs, each of which is enclosed in a fabric pocket in a length of folded fabric material. Longitudinal axes of the coil springs are generally parallel with one another so that the top and bottom end turns of the coil springs define top and bottom faces of the spring assembly. A row of such pocketed springs is known in the industry as a string of pocketed springs. A bedding or seating product can be fabricated from such strings of pocketed springs by binding or adhering the individual rows or strings of pocketed springs together to form a spring assembly which may be padded and encased in an upholstered covering. U.S. Pat. No. 6,143,122, which is fully incorporated herein, discloses one such method of adhesively bonding strings of pocketed springs together to form a pocketed spring assembly.
This type of spring assembly is commonly referred to as a pocketed spring assembly due to the fact that each spring is contained within an individual pocket of fabric material. The construction of strings of pocketed coil springs in each pocket is well known in the art and, for example, is disclosed in U.S. Pat. No. 4,439,977 which is hereby incorporated by reference in its entirety. The system disclosed in that patent includes a spring coiler which forms a coil spring which is subsequently compressed and inserted between the plies of folded pocketing fabric material. Other systems for manufacturing pocketed coil spring assemblies are disclosed in PCT Patent Application No. WO 94/18116 and U.S. Pat. No. 6,101,697, each of which are expressly incorporated herein by reference.
Pocketed spring assemblies are generally recognized to have a unique and particular luxurious feel to them and mattresses manufactured of such pocketed spring assemblies provide a feeling of softness without lacking spring resilience or support. Mattresses and similar articles constructed of pocketed spring assemblies are often considered a high-end type of product because of the added benefits and features of the pocketed coil springs. Mattresses and the like of this type can be more costly to manufacture and assemble as a result of the considerable amount of time and labor which is involved in their manufacture, together with the fact that the method of fabrication and assembly of such pocketed spring assemblies can be complicated, particularly in an automated process.
One particular aspect of pocketed spring assemblies and the associated mattresses or the like is that the resulting product may have a xe2x80x9chardxe2x80x9d feel due to the fact that all of the coil springs are identical and compressed to the same degree in individual pockets. Usually, the firmness of such a product is uniform across the width and along the length of the product.
Additionally, while pocketed spring assemblies are desirably provide a combination of softness and support, the ability to economically posturize a spring assembly or mattress of pocketed spring coils has heretofore been difficult. Posturization provides multiple zones or sections of differing firmnesses within a product such as a mattress. For example, the middle regions of the mattress, which typically support a person""s torso, often require a firmer more resilient support while other areas of the mattress which support the feet and head of a person require a softer feel.
One known method of posturizing a pocketed spring unit has been to incorporate springs made of different gauge wire into the strings of springs. For example, the springs incorporated into the strings of springs within certain sections or zones of the spring assembly are made of a heavier gauge wire than the springs incorporated into the strings of springs of the other sections or zones of the spring assembly. Pat. No. 6,173,464 discloses this concept, albeit with continuous bands of springs as opposed to individual springs.
Therefore, there is a need for a pocketed spring assembly which has an initial soft feel but the firmness necessary to support heavy loads.
There is further a need for a posturized pocketed spring assembly and associated method of manufacture which offers the advantages of posturization of the pocketed spring assembly without the higher manufacturing costs, production difficulties and inefficiencies associated with known posturized pocketed spring assemblies.
The invention of this application comprises a pocketed bedding or seating product and associated method of manufacture. The bedding or seating product comprises a pocketed spring assembly, one or more pads and an upholstered covering surrounding the pocketed spring assembly and pads. The product is preferably two sided and may be used on either side.
The pocketed spring assembly comprises a plurality of parallel strings of springs joined together. Each of the strings of springs comprises a row of interconnected pocketed springs. Each of the pocketed springs comprises a spring surrounded with a pocket of fabric, as is conventional. Although coil springs are preferably used, other types of springs may be used in accordance with the present invention. Each of the coil springs has an upper end turn, a lower end turn and a plurality of central convolutions between the end turns.
Preferably, each string of springs is made of one piece of fabric folded to create two opposed plies which are joined together in select locations to form a plurality of pockets, each of the pockets containing a spring. The opposed plies of fabric of the string of springs may be joined together by sewing, gluing, sonic welding, as known in the art or any other means. Adjacent pockets within a string of springs are separated by generally vertically oriented lines of attachment or seams of the opposed plies to each other. The height of the pocket is determined either by: 1) the distance between the bottom surface of the string of springs and one longitudinal segment of attachment or seam of the opposed plies to each other or 2) the distance between top and bottom seams of the pocket.
In several preferred embodiments of the present invention, each string of springs, or at least long sections of each string of springs, has pockets of the same height along its length. However, the pockets are vertically offset from one another, i.e. located at different heights, due to the location of the seams. In one preferred embodiment, every other pocket of fabric is located slightly above the adjacent pockets of fabric, so that every other pocketed spring is higher than the adjacent pocketed springs in at least some strings of springs. For purposes of this document, the higher pocketed springs will be called xe2x80x9chighxe2x80x9d pocketed springs and the lower pocketed springs will be called xe2x80x9clowxe2x80x9d pocketed springs. Similarly, the higher pockets will be called xe2x80x9chighxe2x80x9d pockets and the lower pockets will be called xe2x80x9clowxe2x80x9d pockets.
When a load is initially placed on the product from above, the xe2x80x9chighxe2x80x9d pocketed springs are the only pocketed springs initially compressed. These xe2x80x9chighxe2x80x9d pocketed springs are initially compressed downwardly until their upper end turns are generally coplanar with the upper end turns of the xe2x80x9clowxe2x80x9d pocketed springs. If the load is sufficient, the xe2x80x9clowxe2x80x9d pocketed springs will be compressed as well as the xe2x80x9chighxe2x80x9d pocketed springs.
Preferably, the springs are identical in a string of springs, i.e. have the same height, diameter, pitch, etc. However, the springs may be different in a string of springs, i.e. have different physical characteristics. Again, although coil springs are preferred, any type of spring may be used in accordance with the present invention.
The concept of the present invention may also be used to posturize a bedding or seating product, i.e., make certain regions or portions firmer than other areas or portions of the bedding or seating product. This is accomplished by grouping together multiple strings of springs of the same configuration. For example, each string of springs in a pocketed spring assembly used in a posturized product may have several xe2x80x9chighxe2x80x9d pocketed coil springs next to each other in a group and a plurality of xe2x80x9clowxe2x80x9d pocketed coil springs in another group. The strings of springs may have any number of such groups of pocketed springs. Each group of pocketed springs is located at the same height, thereby defining one region of a bedding or seating product. The strings of springs of the other regions of the product have pocketed coil springs at different heights so as to impart different firmnesses to the different regions.
In another preferred embodiment of the present invention, the perimeter of the product has pocketed springs which are larger than the springs in an internal portion of the product. The perimeter pocketed springs provide edge support to the product. In one such preferred embodiment having longitudinally extending strings of springs, the outermost strings of springs along the sides of the product have higher pockets containing larger springs along the entire length of the string of springs. The internal strings of springs therebetween have at least one larger pocketed spring at each end of the string of springs, between which may be alternating xe2x80x9chighxe2x80x9d and xe2x80x9clowxe2x80x9d pocketed springs or at least some xe2x80x9clowxe2x80x9d pocketed springs of a lesser height than the perimeter pocketed springs. The xe2x80x9chighxe2x80x9d and xe2x80x9clowxe2x80x9d pocketed springs of a portion of the internal strings of springs are the same height, but vertically offset from one another due to the location of the seams of the pockets. The springs are preferably identical coil springs, although they may be different from one another in some regard.
The bedding or seating product typically has a longitudinal dimension and a transverse dimension, the longitudinal dimension being greater than the transverse dimension. However, the longitudinal dimension and transverse dimension may be identical in a square bedding or seating product. In the invention of the present application, the strings of springs may extend longitudinally or transversely, depending upon the desired effect.
Adjacent strings of springs of the bedding or seating product are preferably glued together but may be otherwise secured to each other. At least one border wire may extend around the perimeter of the pocketed spring assembly of the bedding or seating product and be secured to select outermost pocketed coil springs. A first or lower border may be secured to the lower end turns of the coil springs of the outermost strings. A second or upper border wire may be secured to the upper end turns of the coil springs of the outermost strings or, alternatively, either border wire may be secured to intermediate convolutions of the coil springs of the outermost strings of springs.
Due to select coil springs being pocketed at a higher location than other pocketed coil springs in at least one section or region of the pocketed spring assembly, at least one section of the pocketed spring assembly has a xe2x80x9csoftxe2x80x9d feel when a load is placed thereon. Once such xe2x80x9chighxe2x80x9d pocketed coil springs are compressed to the level of the xe2x80x9clowxe2x80x9d pocketed coil springs, all the pocketed coil springs of the region of the pocketed spring assembly may be compressed, if necessary to support the load.
One method of manufacturing the pocketed spring assembly of the present invention comprises inserting at least one spring between opposed plies of fabric of a string of springs. The opposed plies of the string of springs are then joined in select locations with seams to create a pocket. A plurality of pocketed springs are created in this manner within each string of springs. Each pocket is the same height and contains at least one spring. In one preferred embodiment, every other pocket within the string of springs is vertically offset from adjacent pockets such that every other pocketed coil spring is located slightly above adjacent pocketed coil springs. In such an embodiment, every other spring is located at a height less or greater than the adjacent pocketed springs in the string of springs. The strings of springs are then joined together to form the pocketed spring assembly and the pocketed spring assembly encased in an upholstered covering to create the product.
The method of manufacturing the posturized spring assembly of the present invention varies depending upon the desired posturization. However, in each of the applications of the present invention whenever pocketed springs are vertically spaced above other pocketed springs and incorporated into a portion of a string of springs, that region or section of the pocketed spring assembly has an initial xe2x80x9csoftxe2x80x9d feel when a load is placed thereon. This initial xe2x80x9csoftxe2x80x9d feel is desirable to many customers or users of the product.
In each of the embodiments of the present invention, incorporating pockets of the same height but vertically offset from one another into at least several strings of springs results in a pocketed spring assembly having an initial xe2x80x9csoftxe2x80x9d feel in a portion thereof. Such a product may be made in accordance with a customer""s needs and desires quickly and easily.
These and other objects and advantages of the present invention will be more readily apparent from the following drawings.